Palladium-catalyzed hydroalkylation of methylenecyclopropanes with simple hydrazones

Mother Nature has its own arts to build a vast number of carbohydrates; however, there is still a lack of tools for selective functionalization of native carbohydrates through C─C bond formation. Such a long-standing challenge for the synthetic community lies into the intrinsic problems related to the innate properties of carbohydrates, e.g., the ease to oligomerization or polymerization, the difficulty of chemoselectivity control in the presence of multiple hydroxyl groups, the great challenge to retain the multiple chiral centers during the transformation, etc. Here, by applying an umpolung strategy of carbohydrate carbonyls, we report a direct deoxygenative allylation and olefination of carbohydrates to tackle the abovementioned issues. The reaction is compatible with a wide range of natural carbohydrates, providing a direct synthetic method to use carbohydrates as multiple C-centered chiral synthons to achieve C─C bond cross-coupling reactions. Furthermore, the synthetic applicability is demonstrated by late-stage modifications of natural products and pharmaceutical derivatives.

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“…On the basis of the above results and previous studies ( 15 , 18 , 19 ), a plausible mechanism is proposed in Fig. 5D .…”

Section: Resultssupporting

confidence: 78%

Umpolung carbonyls enable direct allylation and olefination of carbohydrates

et al. 2022

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“…In addition, the Li group and others have demonstrated that other transition‐metal catalysts, including Ni, Pd, and Fe, [29] could efficiently be merged with the WK processes to realize different mechanistic pathways (Scheme 4). This results in a vastly expanded set of accessible coupling partners, such as alkyl halides, [30] dienes, [31] styrenes, [32] phenol derivatives, [33] and aryl halides [34] in Ni catalysis and methylenecyclopropanes, [35] alkynes, [36] allylic acetates, [37] and gem ‐difluorocyclopropanes [38] in Pd catalysis. Several plausible reaction pathways for the different catalytic systems were postulated, as shown in Scheme 4.…”

Section: Catalytic Methods For the Generation Of Alkyl Carbanions Fro...mentioning

confidence: 99%

Catalytic Generation of Carbanions through Carbonyl Umpolung

Wang

König

2021

Angew Chem Int Ed

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Carbonyl Umpolung is a powerful strategy in organic chemistry to construct complex molecules. Over the last few years, versatile catalytic approaches for the generation of acyl anion equivalents from carbonyl compounds have been developed, but methods to obtain alkyl carbanions from carbonyl compounds in a catalytic fashion are still at an early stage. This Minireview summarizes recent progress in the generation of alkyl carbanions through catalytic carbonyl Umpolung. Two different catalytic approaches can be utilized to enable the generation of alkyl carbanions from carbonyl compounds: the catalytic Wolff–Kishner reaction and the catalytic single‐electron reduction of carbonyl compounds and imines. We discuss the reaction scope, mechanistic insights, and synthetic applications of the methods as well as potential future developments.

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“…Apart from alkynes, some highly strained cyclopropanes, such as methylenecyclopropanes [68] and gem ‐difluorocyclopropanes [69] also behaved as unsaturated electrophiles, which were amenable under the Pd‐catalyzed ring‐opening hydrobenzylation conditions.…”

Section: Deoxygenative Functionalizations Of Aldehydes and Ketonesmentioning

confidence: 99%

Deoxygenative Functionalizations of Aldehydes, Ketones and Carboxylic Acids

Huang

2022

Angewandte Chemie

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The simple and efficient conversion of carbonyl compounds into functionalized alkanes via deoxygenation is highly enabling in chemical synthesis. This Review covers the recent methodology development in carbonyl and carboxyl deoxygenative functionalizations, highlighting some representative and significant contributions in this field. These advances are categorized based on the reactivity patterns of some oxygenated feedstock compounds, including aldehydes, ketones and carboxylic acids. Four types of reactive intermediates arising from aldehydes and ketones during the deoxygenation, namely, bis‐electrophiles, carbenoids, bis‐nucleophiles and alkyl radical equivalents, are presented, while the carboxylic acids mainly behave as tris‐electrophiles when deoxygenated. In each subcategory, selected examples are organized according to the type of bond formation and discussed from a generalized mechanistic perspective.

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Palladium-catalyzed hydroalkylation of methylenecyclopropanes with simple hydrazones

Abstract: A palladium-catalyzed hydroalkylation of methylenecyclopropanes via selective C–C σ-bond scission was achieved, in which simple hydrazones served as carbanion equivalents. This method affords high yields of C-alkylated terminal alkenes with good functional group compatibility.

Cited by 29 publications

References 78 publications

Umpolung carbonyls enable direct allylation and olefination of carbohydrates

Umpolung carbonyls enable direct allylation and olefination of carbohydrates

Catalytic Generation of Carbanions through Carbonyl Umpolung

Deoxygenative Functionalizations of Aldehydes, Ketones and Carboxylic Acids

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